Covering material for textile drawing and feeding rolls



July 11, 1944. Ns 2,353,462

COVERING MATERIAL FOR TEXTILE DRAWING AND FEEDING ROLLS Filed Oct. 29, 1941 INVENTOR. HOV/f7 ,6. fiM/Wf/MS' BY M- Patented July 11, 1944 COVERING MATERIAL FOR TEXTILE DRAW ING AND FEEDING ROLLS Henry H. Harkins, North Providence, R. L assignor to United States Rubber Company, New York, N. Y.. a corporation of New Jersey Application October 29, 1941, Serial No. 416,944

' Claims. (Cl. 19-143) This invention relates to drawing and feeding rolls for spinning and other textile machinery, and more particularly to covering material for such rolls.

- Drawing and feeding rolls are extensively used in the manufacture of sliver, roving and yarn, and are commonly arranged in three pairs so that the sliver or roving may pass between the successive pairs which are driven at successively increasing speeds.

Each pair usually consists of a lower roll formed of steel having a fluted or corrugated surface, and an upper or top roll having a softer surface adapted to cooperate with the fluted steel roll to grip the textile fibers.

The upper roll commonly consists of a metal core or arbor provided with a non-metallic cover or cot. These covers or cots for many years have been made of leather or cork, but more recently synthetic rubber has been used to some extent. Most of the rolls in use today however have a leather or cork cover.

The requirements of the cover or cot for these top rolls are highly exacting, since in order to give good service the rolls should be capable of operating for a number of months in the hot, damp atmosphere of the spinning room or other textile room without being injured by this temperature and humidity or by the grease or oil to which they are likely to be exposed. Furthermore, they should be sufllciently soft or yielding to engage the fibers with the desired amount of friction and traction action without causing the fibers to unduly cling to the rolls and wind up upon the same as waste, nor should they become grooved when allowed to rest for relatively long periods upon the lower corrugated steel rolls under considerable pressure.

It is well known that in operating upon textile fibers there is a tendency for such fibers to develop an electric charge or static charge, and'that when such fibers are fed between the ordinary drawing or feeding rolls, an electric charge developed upon the fibers will tend to produce a charge of different potential upon the non-metallic cover of the drawing or feeding rolls. This causes these rolls to attract the fibers and increases the tendency of the loose or broken fibers to wind up upon these rolls to produce waste and interfere with the proper operation of the machines.

Having in mind the foregoing, one important object of the present invention is to provide improved covers or cots for spinning and other textile rolls. Another important object is to provide covers or cots which are sufficiently current conductive todisperse any static charge that may tend to build up upon the same, and thereby reduce the tendency of the fibers to cling to these upper rolls and wind about the same as the result of an electric attraction between the fibers and rolls.

Another object of the present invention is to provide such drawing or feeding rolls with a cover or cot formed of synthetic rubber which is capable of giving excellent service for a long period of time under the severe operating con dition to which they are likely to be subjected on a spinning frame or other textile machine, and which synthetic rubber contains suflicient current conducting carbon to maintain the cover sub tantially free of an electric charge.

e various features of the present invention will be more fully understood from the following description when read in connection with the accompanying drawing illustrating one type of drawing or feeding roll provided with a cover that is formed in accordance with the present invention.

In the drawing:

Fig. 1 is a perspective view of a top drawing or feeding roll provided with a cover or cot made in accordance with the present invention; and

Fig. 2 is a sectional view taken on the lines 2-2 of Fig. 1.

The roll illustrated in the drawing is or may be of well known construction except for the material forming the cover, and is provided with the bosses I0 and II that are connected by the intermediate neck l2, these parts are formed of metal such as steel.

The boss Ill has firmly secured thereupon the tubular cover or cot l3, formed of the material of the present invention, to be described, and the boss I l is provided with a cover or cot it formed of the same material. The covers l3 and H in accordance with the present invention are formed of 'an oil-resistant synthetic rubber containing a current conducting carbon adapted to make the synthetic rubber sufliciently conductive to allow any electric charges that may tend to form upon the cover to be dispersed over its area and to the metal core of the roll l0, H, H, and from this roll to the metal parts of the machine which operatively support this roll.

The synthetic rubber used is preferably of the "Buna type, and more particularly of the type known as Perbunan" (co-polymers of butadiene and acrylonitrile) to which is added softeners, curatives and a conductive carbon such as acetylene carbon black (Shawinigan black) to render the vulcanized composition capable of conducting electricity.

Compositions formed of these materials can be milled, or Banbury mixed, calendered, or tubed, and handled by the conventional methods to give a seamless tube which can be slipped onto the bosses of the textile rolls similar to the way cots are fabricated, or the composition may be formed into a sheet to be wrapped about the roll and firmly secured thereupon. The gauge of the finished rolls can be made highly uniform over the entire face of the roll, and regular cork grinding machines can be used for finishing these synthetic rubber covers; or rubber grinding machines may be used to produce a very smooth uniform roll surface.

The drag, friction or tractive action of a cover formed of this material can be made quite uniform and similar to that presented by a cork or leather cover, and the life of this roll for a given thickness of cover will be several times that of a cork roll used under the same conditions.

The roll cover can be formulated to any desired hardness (Shore A type durometer reading 30 to 100), and the roll cover will withstand oil seepage, moisture, weak acids and mild alkali without swelling and consequent change of gauge. Furthermore compounds of these materials have been provided which afl'ord much better resistance to cutting and grooving by the accumulation of fibers thereupon than cork cots.

The presence of the current conducting carbon throughout the synthetic rubber composition makes the cover suihciently conductive to carry off such electric charges as may tend to form thereupon, and by providing an electrically conductive rubber cement between the present cover and the boss upon which it is mounted a conductive joint is provided between these two which permits any charge upon the cover to reach the metal core or arbor.

The composition herein contemplated also possesses good resistance to cold flow so that it will retain its shape accurately for months of use.

Some of the properties of the compositions herein contemplated such as resiliency, low drift, and resistance to oils may be possessed to a degree by the synthetic rubbers used heretofore as covers or cots for drafting and feeding rolls, but it is believed these combined properties are possessed to a greater degree in the present construction. Furthermore the electrically conducting properties of the present construction provide an important added advantage by reducing the tendency of the fibers to cling to the rolls and wind up thereupon in the form of waste which damages the rolls, interferes with the proper operation of the machine and makes stoppage for clearing of the rolls necessary.

One good practical method of making the roll covers or cots herein contemplated is as follows:

The Perbunan, which is also known as Buna-N, may be refined by passing it several times through a tight mill. The softeners such as oils, asphalts, waxes, stearic acid, dibenzyl ether, Duroplex resin, etc., are then added and milled'in well. The sulfur and accelerator are then added. The stock is then preferably placed in a Banbury mixer and Shawinigan acetylene black is added. and as soon as this black is mixed in, the stock is dumped. It may then be formed into a tube of the required size to form the roll cover or cot. It is important not to disperse the Shawinigan black too thoroughly, as this will reduce its conductivity and cause the stock to.

form of tube stock. The tubed Perbunan stock may be conveniently vulcanized by filling with soapstone and covering over with soapstone and curing in steam under pressure. After curing the tube may be cut to the required length and forced onto the boss of the steel roll, whereupon the edges of the cot thus formed may be trimmed or ground to the desired shape.

It is possible, by giving the tube of cured stock a suificiently small bore, to rely upon its snug fit upon the boss to hold it in place without the use of cement, it is deemed preferable however to provide a cement bond between the boss and cot.

The preferred method of applying the cover to the steel arbor is to employ a cement which when dry will be hard, and preferably will adhere to both the metal arbor and the Perbunan stock. Cements of chlorinated rubber work very satisfactorily for this purpose. It is found that chlorinated rubber dissolved in an aromatic solvent such as xylol, to which is added acetylene carbon black to render the dried cement electrically conducting, makes an excellent cement for holding these cots to the metal center. The cement is brushed on to the steel arbor, and while still wet, the cured Perbunan cot is slipped on to the arbor by means of an arbor press, or by other means.

In developing the present invention one of the problems involved was to impart sufllcient electrically conductive properties to the cover to carry off static charges without overloading the cover forming composition with carbon. To accomplish this it is necessary to use Shawinigan acetylene black or such other black as will provide good conductive properties. The covers I! and II should preferably have a resistivity of megohm-cm. or less to thereby reduce the tendency of the cover to carry a charge of statical electricity, and this resistivity cannot be secured by using the more common carbon blacks without greatly overloading the synthetic rubber mix.

The nature of the stock which it is deemed preferable to use will be more fully understood from the following specific examples wherein the parts are by weight, although it will be understood that the compound used may be varied extensively.

Example I Perbunan Wood rosin 5 Alkyd resin 5 Soft brown factice i0 Dibenzyl ether 10 Shawinigan black 60 Paramn 2 Altax (accelerator) 1.5 Sulfur 5.0

The physical properties of the cured stock of Example I were as follows:

Cure in press Tensile Resistivity Ohmmm. 30 at 33 F I, 143 60 at 33 F 2, 158 20, 000 1% at 303 F 2,

ShoreA durometerhardness-4li.

The p ical properties of the cured stock of Example II were as follows:

Cure in press Tensile Resistivity l Ohms-cm. 3 hrs. at 287 F l. 549 14.0

Shore A durometer hardM. Roll covers or cots formed in accordance with either of the examples above given afford excellent wear in use and reduces to a minim m the tendency of the fibers to wind about the roll.

Where it is found that rolls formed of stock having a resistivity of not much less than /2 megohm-cm. are sufliciently free of static, the stock may be made in accordance with Example I above given except that the Shawinigan black contents is lower.

While textile drawing and feeding rolls for various uses may be constructed in accordance with the present invention. the present rolls are particularly well adapted for use upon machines of the type disclosed in the Foster Patent No. 2,024,156, Elastic yarn and mocess of making the same, where the front roll contacts a tensioned rubber thread as well as the textile fibers and may be subjected to the scoring action of the broken rubber thread woimd upon such roll.

Having thus described my invention, what I claim and desire to protect ivy-Letters Patent is:

1. A textile drawing or feeding roll comprising a metal arbor, and a tubular cover fixed on said arbor, made of a compound including a large amount of a rubber-like co-polymer of butadiene and acrylonitrile'containing a substantial amount of acetylene black that is dispersed to only a moderate degree through the compound to impart to the cover a resistivity of megohm-cm. or less whereby the tendency of the cover to carry a charge of statical electricity is reduced.

2. A tubular cot which can be forced on to a metal arbor and which is composed of an oil resistant composition including a large amount of a synthetic rubber formed of a co-polymer of butadiene and acrylonitrile and containing a substantial amount of acetylene black that is dispersed to only a moderate degree through the composition to provide a resistivity of t; megohm-cm. or less to disperse statical electricity.

3. A fiber engaging roll for textile machinery provided with a composition surface layer formed of an oil resistant compound including a large amount of a synthetic rubber formed of a copolymer of butadiene and acrylonitrile and containing a substantial amount of acetylene black that is dispersed to only a moderate degree through the composition and having a resistivity of megohm-cm. or less to disperse statical electricity.

4. A drawing roll for spinning and roving frames comprising a metal body and a resilient fiber engaging cover thereon, the composition of said cover including, as an essential constituent, a base of butadiene polymerized with acrylic nitrile and compounded with ingredients serving to give it a high degree of elasticity and good resistance to abrasion, and also including as an important constituent a sufllcient proportion of acetylene black to make said cover substantially static free under normal working conditions, said proportion being equivalent to at least 30% of the weight of the base.

5. A drawing roll for spinning and roving frames comprising a metal body and a resilient fiber engaging cover thereon, the composition of said cover including, as an essential constituent, a base of butadiene polymerized with acrylic nitrile and compounded with ingredients serving to give it a high degree of elasticity and good resistance to abrasion, and also including as an important constituent a substantial amount of acetylene black that is dispersed to only a moderate degree through the composition to impart to the material of the cover a resistivity of V2 megohm-cm. or less and make the cover substan- Sally static free under normal working condions.

HENRY H. HARKINS. 

